Abstract for IMM90012 - Oxymetholone (CASRN 434-07-1)

Abstract

The following abstract presents results of a study conducted by a contract laboratory for the National Toxicology Program (NTP). The findings have not been peer reviewed and were not evaluated in accordance with the levels of evidence criteria established by the NTP on March 2009 (see http://ntp.niehs.nih.gov/ntp/htdocs/levels/09-3566%20NTP-ITOX-R1.pdf). The findings and conclusions for this study should not be construed to represent the views of the NTP or the US Government.

Immunotoxicity of Oxymetholone (CAS No. 434-07-1) in Male
B6C3F1 Mice

NTP Report Number IMM90012

Introduction

Oxymetholone is a synthetic androgen, structurally related to testosterone.
Originally, it was used in the treatment of pituitary dwarfism and
adjunctive therapy in osteoporosis. Its current use is limited to
treatment of certain anemias. Anabolic steroids have been taken to improve
strength and orally active anabolic steroids, such as oxymetholone,
represent a class of abused drugs. Since sex steroids, including estrogen
and testosterone, are well known to influence immune function at
pharmacological or suprapharmacological levels the potential effects of
oxymetholone on the immune system of mice were examined.

Design

Oxymetholone was obtained from Sigma Chemical Corp. (Lot #037F0705) and was
determined to be greater than 97% pure by HPLC. The material was prepared in saline
containing 0.5% methylcellulose, and was administered daily for 14
consecutive days at doses of 50, 150, or 300 mg/kg by oral gavage in
volumes of 0.2ml/10g body weight. Control mice received the vehicle and
the positive control group received cyclophosphamide (Sigma Chemical Corp.
Lot #67F-0155) by i.p. injection at daily doses of 25 mg/kg on days 11
through 14 of the study except in the host resistance tests where
cyclophosphamide was administered at a single dose of 200mg/kg on day 14.
Since oxymetholone is a synthetic androgen, male B6C3F1 mice, rather than
female mice were used. On day 15, one day after the last exposure, the
animals were evaluated for the indicated immunological and toxicological
endpoints. Unless indicated, 7-8 mice were examined per treatment group
for each endpoints.

Results

General toxicological and immunological data are summarized in Table 1.
There were no treatment-related effects on mortality, body weights or
selected organ weights including spleen, thymus or liver (latter not
shown). Hematological parameters were not remarkably affected, nor were
serum chemistries (SGPT, glucose, total protein, albumin, globulin)
although BUN levels were slightly elevated at the two higher doses. While
bone marrow cell DNA synthesis in the 300 mg/kg treatment group was
decreased, no effects were seen on cellularity or CFU-C2 progenitor cell
formation (data not shown). There were no oxymetholone-related effects on
the antibody response to sheep erythrocytes, natural killer cell activity,
mitogenic responses to PHA, Con A or LPS, or the numbers of splenic T and B
lymphocytes or T lymphcytes in subsets. The mixed leukocyte response was
suppressed in the high- dose group and there was a slight decrease in the
cytotoxic T lymphocyte response for all doses of oxymetholone.
Macrophages, obtained from the peritoneal cavity of oxymetholone-treated
mice, were equally responsive to activation by interferon-gamma as those
from control mice when assessed by in vitro tumor cell killing (data not
shown).

The ability of animals to resist infection with Listeria monocytogenes was
not significantly compromised by oxymetholone treatment (Table 2).

Conclusion

Under these experimental conditions, the results suggest that treatment
with oxymetholone can result in a mild decrease in cell-mediated immunity.
However, when contrasted to the degree of suppression induced by
cyclosphosphamide, and the limited alterations in other immune functions
associated with oxymetholone exposure, the changes are considered minimal.
The chemical treatment did not affect the ability of the animals to resist
infection in the host resistance tests.

Table 1. Summary of Oxymetholone Immune Studies

Parameter

Dose (mg/kg)

CTX

0

50

150

300

25 mg/kg

Body Weight (g)

28.6

28.2

27.8

28.6

28.1

Spleen (mg)

134

117

139

154

74#

Spleen:Body wt. (%)

0.48

0.41

0.50

0.55

0.26#

Thymus (mg)

55

44

43

49

45

Thymus:Body wt. (%)

0.19

0.15

0.16

0.17

0.16

Spleen cell no.
(x 10E7)

15.4

13.2

14.9

14.1

8.3#

Peripheral Leukocyte Count

(10E3/mm3)

4.6

6.7

4.5

5.6

3.3

Thy 1.2+ (%)

39.2

41.1

47.3

32.8

57.4*

CD4+ (%)

22.6

25.4

26.0

22.0

32.0#

CD8+ (%)

10.8

13.4

13.4

10.6

16.6#

sIg+ (%)

41.7

40.9

41.3

39.3

36.4

Cytotoxic T Lymphocytes

(% cytotoxicity) 25:1

99.6

88.6*

87.5#

84.3#

83.0#

Natural Killer Cell Activity

(% cytotoxicity) 100:1

7.8

ND

9.3

9.2

ND

IgM PFC/10E6

2143

2253

2347

2183

33#

IgM PFC/spleen (x 10E3)

366

432

434

422

4#

Lymphoproliferation:
3H-TdR Incorporation
(cpm x 10E3)

Concanavalin A

107

128

113

87

66

Phytohemagglutinin

94

128

123

76

110

Lipopolysaccharide

11

13

10

9

5*

Mixed Leukocyte Response

47

34

45

29*

12#

Abbreviation: CTX = cyclophosphamide;
* different from vehicle control at P less than 0.05
# different from vehicle control at P less than 0.01
ND = no data